“If you want to increase your success rate, double your failure rate”
— Thomas Watson, Sr. founder of IBM
Spectroscopic analysis is based on an atom or compound’s interaction with electromagnetic radiation of specific wavelength. Spectroscopy provides information on chemical identity of a compound, quantity present and structure based on the technique selected and the wavelength of electromagnetic spectrum. Commonly used spectroscopic techniques in any laboratory are UV –VIS spectroscopy, FT – IR spectroscopy, Atomic Absorption spectroscopy and ICP/ ICP – MS spectroscopy.
This topic will introduce you briefly to the different spectroscopic analysis techniques commonly used in laboratories.
Advantages of spectroscopic techniques
- Rapid analysis – information is available in a matter of seconds as compared to minutes or even hours in other conventional techniques
- Nondestructive – most spectroscopic methods are non-destructive in nature and there is 100%recovery of sample after analysis
- Micro analysis – generally the methods can be adapted to micro volume analysis when quantity of sample is limited.
- High sensitivity –inherent sensitivity of spectroscopic techniques coupled with advances in detection technology provide unparalleled sensitivity. Advancements in hyphenated analytical techniques such as GC – IR, TGA – IR, GC-MS and LC – MS have lowered detection and identification to levels which were not imagined earlier.
- Real-time monitoring – manufacturing processes can be monitored real-time using certain spectroscopic techniques like FT – IR and corrective action can be initiated without the need of sample withdrawal and off-line analysis.
- Spectroscopic detection has been adapted to a number of techniques such as HPLC
Application areas of spectroscopic analysis
Application scope of spectroscopic analysis is virtually unlimited. Knowledge gained in such analysis can contribute to
- Understanding constitution of matter from atoms to complex molecules
- Studies on diverse materials existing in nature from deep sea studies to space missions
- Investigations of crime samples
- Analysis and development of whole range of man-made materials of human consumption
- Studies on environmental samples
Types of spectroscopic analysis
UV – VIS Spectroscopy
Radiation in the UV and visible region of electromagnetic radiation interacts with organic molecules or atoms selectively to give information on presence of absorbing entities. Absorption radiation results in shifts of electrons within the electron levels of atoms and molecules.
FT –IR Spectroscopy
Radiation in the IR region results in changes in bonding in terms of vibration frequencies, rotation and vibration energies depending on the wavelength within the IR region. Such information provides the basis for both qualitative and quantitative levels of IR absorbing groups.
Atomic absorption Spectroscopy
Atomic absorption spectroscopy is based on absorption by ground state atoms of an element present in the sample which is atomised in the flame or graphite furnace. Depending on absorption of selected wavelength of the element the concentration is estimated. The technique provides valuable information on concentration of required elements present in the sample. Concentrations are possible in ppm or ppb levels depending on source of sample excitation.
ICP/ICP – MS
ICP uses a plasma source of excitation of sample. The temperature of the plasma is 2 to 3 orders of magnitude above the flame AAS methods. The technique affords sensitivity upto ppb or even sub ppb levels. ICP – MS technique further extends separation of ionized species based on charge to mass ratio by a quadrupole mass selector. This facilitates analysis of a number of elements that trace levels simultaneously.
You will be introduced to the evolution of Atomic Absorption Spectroscopy in the next post.